PROJECT SUMMARY A conventional prosthetic ankle consists of a carbon fiber ankle-foot complex that is nominally configured to a neutral position. These prostheses generally work well for level walking and level-ground standing, but lack the adaptability to explicitly accommodate other terrain or locomotion activities, such as slope walking, slope standing, and stair ambulation. As such, common activities with a conventional prosthesis can be some of the most daunting and dangerous for individuals with lower limb amputation. This Phase II application describes a microprocessor controlled (MPC) ankle prosthesis for individuals with lower-limb amputation that adapts seamlessly to varying activities and terrain, including slope walking and standing, stair walking, and highly-uneven terrain walking. As a result of this adaptation, the device is expected, and has been shown in preliminary work, to improve safety and enhance stability and comfort across these terrains. The primary goal of this Phase II proposal is to thoroughly assess the value proposition of the proposed prosthesis relative to both conventional prostheses and an MPC damping ankle prosthesis on a number of individuals with lower limb amputation in both laboratory and take-home tests. Doing so will provide a sound, evidence-based foundation for a product launch following this Phase II effort. In order to do so, the investigators propose herein the following three aims: 1) conduct comparative laboratory assessments to quantitatively evaluate the performance of the proposed prosthesis relative to an MPC damping prosthesis and a conventional carbon fiber ankle-foot complex on 10 individuals with lower limb amputation; 2) revise the prosthesis prototype into a premarket device that can support take-home assessments; and 3) evaluate the proposed prosthesis in a series of 2-week take-home assessments on 4 individuals with lower limb amputation.